2-DIMENSIONAL ORDERING OF OCTADECANETHIOL MOLECULES ON GRAPHITE OBSERVED BY SCANNING TUNNELING MICROSCOPE

Molecular-resolution images of n-octadecanethiol monolayer molecules o n a graphite substrate are successfully observed with a scanning tunne ling microscope (STM) in air. The images reveal that the molecules arr ange in a hexagonal p(3 x 3) structure with a periodicity of 7.5 Angst rom, a feature associated with the graphite substrate, X-ray photoelec tron spectroscopy studies suggest that the methyl terminal group is ad sorbed on the graphite. A model for the possible arrangement of the mo lecules on graphite surfaces is proposed. (C) 1997 Elsevier Science B. V.